CN110207822B - High sensitivity optical time delay estimation system, method and medium - Google Patents

Abstract

The invention provides a high-sensitivity optical time delay estimation system, a method and a medium, comprising the following steps: the system comprises a light source module, a polarization state pre-modulation module, an optical time delay sensing module, a combined spectrum detection module and a data processing module; the light source module is used for generating an original light signal, and the central wavelength of the original light signal is recorded as lambda₀(ii) a The polarization pre-modulation module is used for pre-modulating the polarization of an original optical signal to generate first output light; the optical time delay sensing module is used for loading an optical time delay value to be measured to the first output light to generate second output light; the polarization state post-selection module is used for projecting and decomposing the second output light according to the specified polarization state to generate two paths of output light, namely third output light and fourth output light. The invention adopts a method of 'joint bias weak value amplification', realizes the measurement of tiny quantity such as time delay with extremely high sensitivity, and also provides a high-sensitivity measurement scheme for other optical parameter estimation tasks.

Description

High sensitivity optical time delay estimation system, method and medium

technical field

The present invention relates to the measurement technology of tiny physical quantities, in particular, to a high-sensitivity optical time delay estimation system, method and medium. In particular, it relates to an optical time delay estimation system based on joint weak value amplification technology, which can be applied to realize optical precision measurement, such as optical coherence tomography, etc., to improve resolution and detection sensitivity.

Background technique

In the field of precision measurement, weak measurement techniques are mainly divided into two categories: weak value amplification weak measurement and joint weak measurement. Among them, the weak value amplification weak measurement technology was proposed earlier, and this technology has been widely used. But inevitably, this technology also has some flaws, such as:

1. Weak value amplification Weak measurement uses weak coupling and post-selection technology to properly amplify the originally very small parameter to an observable position, so as to indirectly measure the small amount. This "amplification" is to choose after sacrifice That is to say, when the post-selection angle is closer to the perpendicular to the pre-selection angle, the magnification will be larger, but the number of photons received on the detector will be less, and the amount of information that can be used will be greater. Small.

2. In the weak measurement of weak value amplification, the calculation of the magnification depends on the post-selection angle. Although the post-selection angle can be known in advance, in the experiment, once the post-selection polarizer is disturbed, the post-selection angle will deviate from the true value. , then the measurement accuracy will be biased.

It can be seen from the above description that the weak value amplification schemes all have some insurmountable defects. In recent years, some scholars have proposed a parameter estimation method based on joint weak measurement. This method is based on weak value amplification and weak measurement. The difference is that the combined weak measurement divides the light after the post-selection into two paths, and measures all photons at the same time. In this way, all photon information can be collected and the measurement can be improved. In addition, the joint weak measurement uses the post-processing algorithm of maximum likelihood estimation to obtain the offset. This method can estimate the small parameters and the post-selection parameters at the same time when the post-selection parameters are unknown. In this way, even under experimental conditions The post-selection parameters are not stable, and the method of joint weak measurement will not affect the accuracy of parameter estimation. Therefore, the combined weak measurement can effectively make up for the defect of weak value amplification of weak measurement. However, the joint weak measurement method also has the following shortcomings:

1) When setting the same weak value magnification, the offset is only half of the traditional weak value amplification method (the sensitivity is reduced by half);

2) Higher weak value magnification cannot be obtained by modulating the bias phase.

It can be seen that the two existing weak measurement schemes, weak value amplification and joint weak measurement, have inherent shortcomings. The invention proposes a new method for realizing the estimation of weak measurement parameters, which can organically combine the advantages of the weak value amplification and the joint weak measurement, and learn from each other's strengths to complement each other, which can not only overcome the low efficiency of the weak value amplification scheme, but also solve the The problem that the magnification of the combined weak measurement scheme is difficult to increase provides a reliable technical approach for the use of high-efficiency and high-sensitivity parameter measurement.

Patent document CN107121207A (application number: 201610101252.2) discloses a time delay estimation method and system based on joint weak measurement technology, including: an optical module, a data acquisition module and a data processing module; wherein, the optical module is used to The measurement parameter estimation algorithm estimates the time delay; the data acquisition module is used to control the spectrometer to collect data; the data processing module is used to analyze and process the measurement data to obtain an estimated value of the time delay.

SUMMARY OF THE INVENTION

In view of the defects in the prior art, the purpose of the present invention is to provide a high-sensitivity optical time delay estimation system, method and medium.

A high-sensitivity optical delay estimation system provided according to the present invention includes: a light source module, a polarization state pre-modulation module, an optical delay sensing module, a joint spectrum detection module and a data processing module;

The light source module is used to generate the original optical signal, and its center wavelength is denoted as λ ₀ ;

The polarization pre-modulation module is used to pre-modulate the polarization of the original optical signal to generate the first output light;

The optical delay sensing module is used to load the optical delay value to be measured into the first output light to generate the second output light;

The polarization state post-selection module is used to project and decompose the second output light according to the specified polarization state to generate two output lights, namely the third output light and the fourth output light;

The joint spectrum detection module is used for performing spectrum detection on the third output light and the fourth output light at the same time, and outputting a spectrum signal;

The data processing module collects and stores the output spectral signal, and analyzes and processes the collected spectral signal to obtain an estimated value of the time delay.

Preferably, the polarization pre-modulation module comprises: a linear polarizer (1) and a first quarter-wave plate (2),

The polarization pre-modulation module:

夹角，所述第一输出光的偏振状态记作前选择态，记号表达为：The original optical signal generated by the light source module is passed through the linear polarizer (1) and the first quarter-wave plate (2) to generate the first output light, and the direction of the linear polarizer is set to be a first preset with the horizontal plane The included angle, the direction of the quarter wave plate is set to be in the direction of the linear polarizer

The included angle, the polarization state of the first output light is denoted as the preselected state, and the symbol is expressed as:

in,

表示前选择偏振态；

represents the preselected polarization state;

|H>, |V> represent the horizontal polarization state and the vertical polarization state, respectively;

ε represents a real value much less than 1;

e ^-iCε represents the modulation phase value -Cε;

e ^iCε represents the modulation phase value Cε;

The phase value C that needs to be modulated is calculated by:

in,

ω represents the angular frequency of the optical signal,

ω ₀ represents the average value of the angular frequency of the optical signal.

The optical time delay sensing module includes: a Sorey-Barbinet compensator (3);

The optical delay sensing module: the first output light is passed through a Sore-Barbinet compensator to generate the second output light;

The direction of the Soleil-Barbinet compensator is set to form a second preset angle with the linear polarizer, and compared with the first output light, the horizontal polarization component and the vertical polarization component of the second output light are increased. There is a propagation delay, and this delay is recorded as τ.

Preferably, the polarization state post-selection module includes: a second quarter-wave plate (4) and a polarization beam splitter (5);

The polarization state post-selection module: passing the second output light through the second quarter-wave plate (4) and the polarization beam splitter (5) to generate two output lights, namely the third output light and the fourth output Light;

The direction of the second quarter-wave plate is set to form a third preset angle with the linear polarizer, and the polarization direction of the polarization beam splitter is set to form a fourth preset angle to the linear polarizer.

Preferably, the combined spectrum detection module comprises: a first fiber collimator (6), a second fiber collimator (7) and a spectrometer (8) with an optical switch module;

The joint spectrum detection module: the two output lights generated by the polarization state post-selection module are respectively entered into the optical fiber connected to the spectrometer through the optical fiber coupling device, and then collected by the spectrometer to obtain spectral information;

The spectral distribution of the transmitted light collected by the spectrometer is:

P ₁ (λ _i ) represents the wavelength distribution of the transmitted light signal spectrum;

P ₀ (λ _i ) represents the wavelength distribution of the initial optical signal spectrum;

λ ₀ represents the average wavelength, calculated by the formula ∑ _i P(λ _i )λ _i

λ _i represents a certain wavelength scale value that can be detected by the spectrometer;

c is the speed of light in vacuum;

ε represents a real value much less than 1;

τ represents the optical time delay;

A _w1 (λ _i ) represents a complex value and is calculated by:

Im[A _w1 (λ _i )] represents the imaginary part of A _w1 (λ _i );

The spectral distribution of the reflected light collected by the spectrometer is:

P ₂ (λ _i ) represents the wavelength distribution of the reflected light signal spectrum;

A _w2 (λ _i ) represents a complex value and is calculated by:

Im[A _w2 (λ _i )] represents the imaginary part of A _w2 (λ _i ).

Preferably, the data processing module collects and stores the spectral information obtained by the joint spectral detection module;

According to the spectral information obtained by the joint spectral detection module, the following average wavelength values are defined and calculated:

表示按测量数据计算得到的平均波长值；

Indicates the average wavelength value calculated according to the measurement data;

An estimate of the time delay is solved by the following formula:

in,

τ represents the optical delay to be measured, that is, the estimated value of the time delay;

c is the speed of light in vacuum;

减去输入光的初始波长值λ₀得到。δλ represents the wavelength offset, by dividing the average wavelength value

It is obtained by subtracting the initial wavelength value λ ₀ of the input light.

A high-sensitivity optical time delay estimation method provided according to the present invention includes: a light source generating step, a polarization state pre-modulation step, an optical time delay sensing step, a joint spectrum detection step, and a data processing step;

The light source step is used to generate the original optical signal, and its central wavelength is denoted as λ ₀ ;

The polarization pre-modulation step is used to pre-modulate the polarization of the original optical signal to generate the first output light;

The optical delay sensing step is used to load the optical delay value to be measured into the first output light to generate the second output light;

The post-polarization state selection step is used to project and decompose the second output light according to the specified polarization state to generate two output lights, namely the third output light and the fourth output light;

The joint spectral detection step is used to perform spectral detection on the third output light and the fourth output light simultaneously, and output a spectral signal;

The data processing step collects and stores the output spectral signal, and analyzes and processes the collected spectral signal to obtain an estimated value of the time delay.

Preferably, the polarization pre-modulation step:

夹角，所述第一输出光的偏振状态记作前选择态，记号表达为：The original optical signal generated by the light source generating step is passed through the linear polarizer (1) and the first quarter-wave plate (2) to generate the first output light, and the direction of the linear polarizer is set to be in a first pre-position with the horizontal plane. Set the angle, the direction of the quarter wave plate is set to be in the direction of the linear polarizer.

The included angle, the polarization state of the first output light is denoted as the preselected state, and the symbol is expressed as:

in,

表示前选择偏振态；

represents the preselected polarization state;

|H>, |V> represent the horizontal polarization state and the vertical polarization state, respectively;

ε represents a real value much less than 1;

e ^-iCε represents the modulation phase value -C;

e ^iCε represents the modulation phase value C;

The phase value C that needs to be modulated is calculated by:

in,

ω represents the angular frequency of the optical signal,

ω ₀ represents the average value of the angular frequency of the optical signal;

The optical time delay sensing step: making the first output light pass through the Soleil-Barbinet compensator (3) to generate the second output light;

The direction of the Soleil-Barbinet compensator is set to form a second preset angle with the linear polarizer, and compared with the first output light, the horizontal polarization component and the vertical polarization component of the second output light are increased. There is a propagation delay, and this delay is recorded as τ.

Preferably, the polarization state post-selection step: passing the second output light through the second quarter-wave plate (4) and the polarization beam splitter (5) to generate two output lights, namely the third output light and the the fourth output light;

The direction of the second quarter wave plate is set to form a third preset angle with the linear polarizer, and the polarization direction of the polarization beam splitter is set to form a fourth preset angle with the linear polarizer;

The joint spectrum detection step: the two output lights generated by the polarization state post-selection step are respectively entered into the optical fiber connected to the spectrometer through the optical fiber coupling device, and then collected by the spectrometer to obtain spectral information;

The spectral distribution of the transmitted light collected by the spectrometer is:

P ₁ (λ _i ) represents the wavelength distribution of the transmitted light signal spectrum;

P ₀ (λ _i ) represents the wavelength distribution of the initial optical signal spectrum;

λ ₀ represents the average wavelength, calculated by the formula ∑ _i P(λ _i )λ _i

λ _i represents a certain wavelength scale value that can be detected by the spectrometer;

c is the speed of light in vacuum;

ε represents a real value much less than 1;

τ represents the optical time delay;

A _w1 (λ _i ) represents a complex value and is calculated by:

Im[A _w1 (λ _i )] represents the imaginary part of A _w1 (λ _i );

The spectral distribution of the reflected light collected by the spectrometer is:

P ₂ (λ _i ) represents the wavelength distribution of the reflected light signal spectrum;

A _w2 (λ _i ) represents a complex value and is calculated by:

Im[A _w2 (λ _i )] represents the imaginary part of A _w2 (λ _i ).

Preferably, the data processing step collects and stores the spectral information obtained in the joint spectral detection step;

According to the spectral information obtained by the joint spectral detection step, the following average wavelength values are defined and calculated:

表示按测量数据计算得到的平均波长值；

Indicates the average wavelength value calculated according to the measurement data;

An estimate of the time delay is solved by the following formula:

in,

τ represents the optical delay to be measured, that is, the estimated value of the time delay;

c is the speed of light in vacuum;

减去输入光的初始波长值λ₀得到。δλ represents the wavelength offset, by dividing the average wavelength value

It is obtained by subtracting the initial wavelength value λ ₀ of the input light.

A computer-readable storage medium storing a computer program according to the present invention is characterized in that, when the computer program is executed by a processor, the steps of any one of the above-mentioned high-sensitivity optical time delay estimation methods are implemented.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention can organically combine the advantages of the weak value amplification and the joint weak measurement scheme, and learn from each other's strengths to complement each other, which can not only overcome the low efficiency of the weak value amplification scheme, but also solve the problem that the combined weak measurement scheme is difficult to increase the magnification. The use of high-efficiency, high-sensitivity parametric measurements provides a reliable technical approach.

2. The method of "joint bias weak value amplification" is adopted in the present invention, which realizes extremely sensitive measurement of minute quantities such as time delay, and also provides a highly sensitive measurement scheme for other optical parameter estimation tasks.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

1 is a schematic diagram of a time delay structure based on joint weak measurement provided by the present invention;

2 is a schematic diagram of an initial spectrum of a Gaussian distributed optical signal provided by the present invention;

3 is a schematic diagram of an initial spectrum of a non-Gaussian distributed optical signal provided by the present invention;

4 is a schematic diagram of a spectral shift rate obtained by simulation of a Gaussian distributed light source provided by the present invention;

Fig. 5 is the partial enlarged schematic diagram of the spectral shift rate obtained by the simulation of the Gaussian distributed light source provided by the present invention;

Fig. 6 is the spectral shift rate obtained by the simulation of the non-Gaussian distribution light source provided by the present invention;

FIG. 7 is a partially enlarged schematic diagram of the spectral shift rate obtained by the simulation of the non-Gaussian distribution light source provided by the present invention.

The figure shows:

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the inventive concept. These all belong to the protection scope of the present invention.

A high-sensitivity optical delay estimation system provided according to the present invention includes: a light source module, a polarization state pre-modulation module, an optical delay sensing module, a joint spectrum detection module and a data processing module;

The light source module is used to generate the original optical signal, and its center wavelength is denoted as λ ₀ ;

The polarization pre-modulation module is used to pre-modulate the polarization of the original optical signal to generate the first output light;

The optical delay sensing module is used to load the optical delay value to be measured into the first output light to generate the second output light;

The polarization state post-selection module is used to project and decompose the second output light according to the specified polarization state to generate two output lights, namely the third output light and the fourth output light;

The joint spectrum detection module is used for performing spectrum detection on the third output light and the fourth output light at the same time, and outputting a spectrum signal;

The data processing module collects and stores the output spectral signal, and analyzes and processes the collected spectral signal to obtain an estimated value of the time delay.

Specifically, the polarization pre-modulation module includes: a linear polarizer (1) and a first quarter-wave plate (2),

The polarization pre-modulation module:

夹角，所述第一输出光的偏振状态记作前选择态，记号表达为：The original optical signal generated by the light source module is passed through the linear polarizer (1) and the first quarter-wave plate (2) to generate the first output light, and the direction of the linear polarizer is set to be a first preset with the horizontal plane The included angle, the direction of the quarter wave plate is set to be in the direction of the linear polarizer

The included angle, the polarization state of the first output light is denoted as the preselected state, and the symbol is expressed as:

in,

表示前选择偏振态；

represents the preselected polarization state;

|H>, |V> represent the horizontal polarization state and the vertical polarization state, respectively;

ε represents a real value much less than 1;

e ^-iCε represents the modulation phase value -Cε;

e ^iCε represents the modulation phase value Cε;

The phase value C that needs to be modulated is calculated by:

in,

ω represents the angular frequency of the optical signal,

ω ₀ represents the average value of the angular frequency of the optical signal.

The optical time delay sensing module includes: a Sorey-Barbinet compensator (3);

the optical time delay sensing module: the first output light is passed through a Soleil-Barbinet compensator to generate the second output light;

The direction of the Soleil-Barbinet compensator is set to form a second preset angle with the linear polarizer, and compared with the first output light, the horizontal polarization component and the vertical polarization component of the second output light are increased. There is a propagation delay, and this delay is recorded as τ.

Specifically, the polarization state post-selection module includes: a second quarter-wave plate (4) and a polarization beam splitter (5);

The polarization state post-selection module: passing the second output light through the second quarter-wave plate (4) and the polarization beam splitter (5) to generate two output lights, namely the third output light and the fourth output Light;

The direction of the second quarter-wave plate is set to form a third preset angle with the linear polarizer, and the polarization direction of the polarization beam splitter is set to form a fourth preset angle to the linear polarizer.

Specifically, the combined spectrum detection module includes: a first fiber collimator (6), a second fiber collimator (7), and a spectrometer (8) with an optical switch module;

The joint spectrum detection module: the two output lights generated by the polarization state post-selection module are respectively entered into the optical fiber connected to the spectrometer through the optical fiber coupling device, and then collected by the spectrometer to obtain spectral information;

The spectral distribution of the transmitted light collected by the spectrometer is:

P ₁ (λ _i ) represents the wavelength distribution of the transmitted light signal spectrum;

P ₀ (λ _i ) represents the wavelength distribution of the initial optical signal spectrum;

λ ₀ represents the average wavelength, calculated by the formula ∑ _i P(λ _i )λ _i

λ _i represents a certain wavelength scale value that can be detected by the spectrometer;

c is the speed of light in vacuum;

ε represents a real value much less than 1;

τ represents the optical time delay;

A _w1 (λ _i ) represents a complex value and is calculated by:

Im[A _w1 (λ _i )] represents the imaginary part of A _w1 (λ _i );

The spectral distribution of the reflected light collected by the spectrometer is:

P ₂ (λ _i ) represents the wavelength distribution of the reflected light signal spectrum;

A _w2 (λ _i ) represents a complex value and is calculated by:

Im[A _w2 (λ _i )] represents the imaginary part of A _w2 (λ _i ).

Specifically, the data processing module collects and stores the spectral information obtained by the joint spectral detection module;

According to the spectral information obtained by the joint spectral detection module, the following average wavelength values are defined and calculated:

表示按测量数据计算得到的平均波长值；

Indicates the average wavelength value calculated according to the measurement data;

An estimate of the time delay is solved by the following formula:

in,

τ represents the optical delay to be measured, that is, the estimated value of the time delay;

c is the speed of light in vacuum;

减去输入光的初始波长值λ₀得到。δλ represents the wavelength offset, by dividing the average wavelength value

It is obtained by subtracting the initial wavelength value λ ₀ of the input light.

The high-sensitivity optical time delay estimation system provided by the present invention can be realized through the steps of the high-sensitivity optical time delay estimation method provided by the present invention. Those skilled in the art can understand the high-sensitivity optical time delay estimation method as a preferred example of the high-sensitivity optical time delay estimation system.

According to a high-sensitivity optical time delay estimation method provided by the present invention, the method includes: a light source generating step, a polarization state pre-modulation step, an optical time delay sensing step, a joint spectrum detection step, and a data processing step;

The light source step is used to generate the original optical signal, and its central wavelength is denoted as λ ₀ ;

The polarization pre-modulation step is used to pre-modulate the polarization of the original optical signal to generate the first output light;

The optical delay sensing step is used to load the optical delay value to be measured into the first output light to generate the second output light;

The post-polarization state selection step is used to project and decompose the second output light according to the specified polarization state to generate two output lights, namely the third output light and the fourth output light;

The joint spectral detection step is used to perform spectral detection on the third output light and the fourth output light simultaneously, and output a spectral signal;

The data processing step collects and stores the output spectral signal, and analyzes and processes the collected spectral signal to obtain an estimated value of the time delay.

Specifically, the polarization pre-modulation step:

夹角，所述第一输出光的偏振状态记作前选择态，记号表达为：The original optical signal generated by the light source generating step is passed through the linear polarizer (1) and the first quarter-wave plate (2) to generate the first output light, and the direction of the linear polarizer is set to be in a first pre-position with the horizontal plane. Set the angle, the direction of the quarter wave plate is set to be in the direction of the linear polarizer.

The included angle, the polarization state of the first output light is denoted as the preselected state, and the symbol is expressed as:

in,

表示前选择偏振态；

represents the preselected polarization state;

|H>, |V> represent the horizontal polarization state and the vertical polarization state, respectively;

ε represents a real value much less than 1;

e ^-iCε represents the modulation phase value -C;

e ^iCε represents the modulation phase value C;

The phase value C that needs to be modulated is calculated by:

in,

ω represents the angular frequency of the optical signal,

ω ₀ represents the average value of the angular frequency of the optical signal;

The optical time delay sensing step: making the first output light pass through the Soleil-Barbinet compensator (3) to generate the second output light;

The direction of the Soleil-Barbinet compensator is set to form a second preset angle with the linear polarizer, and compared with the first output light, the horizontal polarization component and the vertical polarization component of the second output light are increased. There is a propagation delay, and this delay is recorded as τ.

Specifically, the polarization state post-selection step: passing the second output light through the second quarter-wave plate (4) and the polarization beam splitter (5) to generate two output lights, namely the third output light and the the fourth output light;

The direction of the second quarter wave plate is set to form a third preset angle with the linear polarizer, and the polarization direction of the polarization beam splitter is set to form a fourth preset angle with the linear polarizer;

The joint spectrum detection step: the two output lights generated by the polarization state post-selection step are respectively entered into the optical fiber connected to the spectrometer through the optical fiber coupling device, and then collected by the spectrometer to obtain spectral information;

The spectral distribution of the transmitted light collected by the spectrometer is:

P ₁ (λ _i ) represents the wavelength distribution of the transmitted light signal spectrum;

P ₀ (λ _i ) represents the wavelength distribution of the initial optical signal spectrum;

λ ₀ represents the average wavelength, calculated by the formula ∑ _i P(λ _i )λ _i

λ _i represents a certain wavelength scale value that can be detected by the spectrometer;

c is the speed of light in vacuum;

ε represents a real value much less than 1;

τ represents the optical time delay;

A _w1 (λ _i ) represents a complex value and is calculated by:

Im[A _w1 (λ _i )] represents the imaginary part of A _w1 (λ _i );

The spectral distribution of the reflected light collected by the spectrometer is:

P ₂ (λ _i ) represents the wavelength distribution of the reflected light signal spectrum;

A _w2 (λ _i ) represents a complex value and is calculated by:

Im[A _w2 (λ _i )] represents the imaginary part of A _w2 (λ _i ).

Specifically, the data processing step collects and stores the spectral information obtained by the joint spectral detection step;

According to the spectral information obtained by the joint spectral detection step, the following average wavelength values are defined and calculated:

表示按测量数据计算得到的平均波长值；

Indicates the average wavelength value calculated according to the measurement data;

An estimate of the time delay is solved by the following formula:

in,

τ represents the optical delay to be measured, that is, the estimated value of the time delay;

c is the speed of light in vacuum;

减去输入光的初始波长值λ₀得到。δλ represents the wavelength offset, by dividing the average wavelength value

It is obtained by subtracting the initial wavelength value λ ₀ of the input light.

A computer-readable storage medium storing a computer program according to the present invention is characterized in that, when the computer program is executed by a processor, the steps of any one of the above-mentioned high-sensitivity optical time delay estimation methods are implemented.

Hereinafter, the present invention will be described in more detail through preferred examples.

Preferred Example 1:

According to the new method for joint weak value amplification with extremely high sensitivity provided by the present invention, the time delay estimation system based on the joint weak measurement technique described in any one of the above is applied; including the following steps:

Polarization pre-modulation and optical time delay sensing steps: process the light emitted by the light source to obtain the reflected light and transmitted light signal spectra related to the parameters to be measured;

Post-polarization selection step: used to project and decompose the optical signal according to the specified polarization state;

Joint spectral detection step: used to perform spectral detection on two output optical signals at the same time;

Data acquisition and processing steps: control the process of spectral signal acquisition to realize the acquisition and storage of spectral signals; analyze and process the spectral signals collected in the data acquisition step to obtain an estimated value of time delay.

Preferably, the polarization pre-modulation and optical delay sensing steps include:

夹角，输出光的偏振状态记作前选择态，记号表达为：Step A1: Pre-selecting the polarization state of the light source signal light. Specifically, the light emitted by the superluminescent light emitting diode light source is passed through the linear polarizer and the quarter-wave plate to generate output light. The direction of the linear polarizer is set at an angle of 45° with the horizontal plane, and the direction of the quarter wave plate is set at an angle of 45° with the direction of the linear polarizer.

The included angle, the polarization state of the output light is recorded as the preselected state, and the notation is expressed as:

记号

表示前选择态，|H>和|V>分别表示水平偏振和垂直偏振态；in,

mark

represents the preselected state, |H> and |V> represent the horizontal and vertical polarization states, respectively;

Step A2: Generate weak coupling. Specifically, the light in the preselected state is passed through a Soleil-Barbinet compensator to generate output light. The direction of the Sore-Barbinet compensator is set to form an included angle of 45° with the linear polarizer. Compared with the input light, a propagation delay is added between the horizontal polarization component and the vertical polarization component of the output light, and this delay is recorded as τ

Preferably, the post-selecting step of the polarization state includes:

Step B: After selecting the polarization state of the optical signal output in the previous step. Specifically, the optical signal output in the previous step is passed through the second quarter-wave plate and the polarization beam splitter to generate two output lights. The direction of the second quarter wave plate is set at an angle of 45° with the linear polarizer, and the polarization direction of the polarization beam splitter is set at an angle of 0° with the linear polarizer. The two output lights are respectively recorded as transmitted light and reflected light.

Preferably, the joint spectrum detection step includes:

Step C: Joint Weak Measurement Process. Specifically, the two output lights generated in the previous step are respectively entered into the optical fiber connected to the spectrometer through the optical fiber coupling device, and then collected by the spectrometer.

The spectral distribution of the transmitted light collected by the spectrometer is:

The spectral distribution of the reflected light collected by the spectrometer is:

where the weak value magnifications A _w1 (λ) and A _w2 (λ) are defined by:

Preferably, the data collection and processing steps include:

Step D1: connect the computer with the optical switch and the spectrum analyzer through the IP network;

Step D2: realize serial communication with the optical switch and the spectrum analyzer on the Labview platform or FPGA by calling the dynamic link library function. On this basis, a program is written to control the parameter setting of the spectrum analyzer, control the switching of the optical switch and the acquisition of the spectrum analyzer data. Save the collected spectral data and the output data of the built-in analysis function of the spectrum analyzer as a file.

Step D3: According to the light intensity distribution obtained in Step C, the maximum likelihood estimation method is used to obtain the estimated value of the time delay. Specifically, according to the light intensity distribution obtained in the data collection step, the following average wavelength values are defined and calculated:

Then, use the following formula to calculate the delay value to be estimated:

减去输入光的初始波长值λ₀得到。In the formula, τ represents the optical time delay to be measured, c represents the speed of light in vacuum, δλ represents the wavelength offset, and the average wavelength value calculated by step C is

It is obtained by subtracting the initial wavelength value λ ₀ of the input light.

Preferred example 2:

The parameter estimation method based on the joint weak value amplification technology and its application scheme in high-precision optical time delay detection provided by the invention adopt the methods of pre-bias selection, joint measurement and calculation of the average wavelength offset value to obtain unknown parameters.

In this embodiment, the micro-delay measurement system with extremely high sensitivity provided by the present invention includes: an optical module, a data acquisition module and a data processing module; wherein the optical module is used for corresponding processing of the light emitted by the signal source , obtain the spectrum of the transmitted light and reflected light corresponding to the signal source; the data acquisition module is used to control the optical module to realize the collection and storage of spectral signals; the data processing module is used to collect the spectral signals collected by the data acquisition module Analysis and processing are performed to obtain an estimate of the time delay.

The specific process of the optical module for generating the time delay is as follows:

As shown in Figure 1, the laser source is an SLD light source with a central wavelength of 1540 nm and a line width of 25 nm. After passing through a polarizer, it becomes linearly polarized light, and the polarizer can be a Glan-Taylor prism. The beam then passes through the first quarter-wave plate, which forms an angle with the polarizer as described above, completing the pre-selection stage.

In the experiment, the initial state of the system is

为前选择态，|H>和|V>分别为水平极化和垂直极化态。in,

is the preselected state, and |H> and |V> are the horizontally and vertically polarized states, respectively.

After the light beam is preselected, it is incident on a birefringent crystal whose main axis is perpendicular to the horizontal plane. When the birefringent crystal takes the optical axis as the axial direction and rotates counterclockwise by a certain angle θ, the horizontal polarization component of the preselected light and the vertical There will be a very weak time delay between the polarization components, which can be expressed as

Among them, n _e , n _o and n are e light, o light and the average refractive index, respectively, c is the speed of light, and λ is the frequency of the incident light.

The above formula establishes the relationship between the time delay τ and the tilt angle θ. Different time delays can be obtained by controlling the tilt angle of the birefringent crystal in the experiment.

After the time delay is generated, the light beam passes through a second quarter-wave plate and a polarizing polarizer (PBS). The quarter-wave plate is adjusted to form an angle of 45° with the polarizer, and the polarization axis of the polarization beam splitter is adjusted to the same direction as the polarizer. Combined with the direction setting of the wave plate, the light intensities received by the two spectrometers are approximately equal at zero offset, which satisfies the design of joint weak measurement.

In the example, after post-selection, the post-selection states of the two directions are

和

分别为透射光和反射光的后选择态，φ为偏振分束器的极化角度。经过后选择后，两路光的弱值分别记为A_w1、A_w2，计算公式如下：in,

and

are the post-selected states of transmitted light and reflected light, respectively, and φ is the polarization angle of the polarizing beam splitter. After post-selection, the weak values of the two paths of light are recorded as A _w1 and A _w2 respectively, and the calculation formula is as follows:

After post-selection, the distribution of the probability of the photons of the two beams of light being detected on the spectrum is:

where P ₁ (ω) and P ₂ (ω) represent the spectra of the two beams, respectively, and P ₀ (ω)=|f ₀ (ω)| ² is the initial spectrum of the light beam, and its average value is ω ₀ .

The specific process of the data acquisition module is as follows:

This LABVIEW or FPGA-based data acquisition system can control the spectrometer and optical switch to collect spectral data. First, use routers and other equipment to connect the computer firmly to the optical switch and spectrum analyzer, and start the computer, optical switch, and spectrum analyzer. In the Labview program, judge whether the communication with the computer serial port is normal by observing whether the serial port displays the name of the optical switch and the spectrum analyzer. The Labview program written by the program sends commands to the spectrum analyzer to input the settings and scans the spectrum. The program simultaneously controls the switching of the optical switch and cooperates with the spectrum analyzer to receive the two paths of light output from the polarization beam splitter. The main settings for the spectrum analyzer in this example are: 500 sampling points, HIGH1 sensitivity, auto level, sampling center at 1577 nm and scan width at 100 nm. The program obtains the spectral data fed back from the spectrum analyzer and the output data of the built-in analysis function through the serial port, and then saves it in a file.

The specific process of the data processing module is as follows: the collected data is processed by writing codes. In the example, when we obtain the spectral distribution functions of the two paths of light, the above algorithm can be used to estimate the time delay to be measured in the propagation direction between the horizontal component and the vertical component of the cross-section after the light passes through the optical delay module. τ value. Read the spectral data from the file and calculate the average wavelength according to the following formula:

In the formula, P ₁ (λ _i ) and P ₂ (λ _i ) represent the spectral intensities of the received two paths of light respectively, and λ _i represents each sampling point of the wavelength by the spectrum analyzer.

Then the optical delay value can be calculated as follows:

减去输入光的初始平均波长值λ₀得到，λ₀依光源特性不同而变化，在实例中由光谱分析仪测定。In the formula, τ represents the optical time delay to be measured, c represents the speed of light in vacuum, δλ represents the wavelength offset, and the average wavelength value obtained by calculating

It is obtained by subtracting the initial average wavelength value λ ₀ of the input light, which _varies with the characteristics of the light source and is measured by a spectrum analyzer in the example.

Preferred example 3:

The extremely high sensitivity optical delay estimation system based on joint weak value amplification provided according to the present invention is characterized by comprising a light source module, a polarization state premodulation module, an optical delay sensing module, a joint spectrum detection module and a data processing module, wherein :

1. The light source module includes a superluminescent light emitting diode, which is used to generate the original light signal.

Specifically, the superluminescent light-emitting diode generates a high-power broadband beam, the central wavelength of which is denoted as λ ₀ ;

2. The polarization pre-modulation module includes a linear polarizer and a first quarter-wave plate for pre-modulating the polarization of the signal light;

Specifically, the original optical signal passes through the linear polarizer and the first quarter-wave plate set at a specific angle, and outputs a beam of previously selected polarization state.

3. The optical delay sensing module includes a Soleil-Barbinet compensator, which is used to load the optical delay value to be measured into the signal light;

Specifically, the light beam with the preselected polarization state passes through a Sorey-Barbinet compensator, and outputs a light beam with time delay information.

4. The polarization state post-selection module includes a second quarter-wave plate and a polarization beam splitter, which is used to project and decompose the optical signal according to the specified polarization state;

Specifically, the light beam with time delay information passes through a second quarter-wave plate and a polarization beam splitter arranged at a specific angle, and outputs two light beams with mutually perpendicular polarization states.

5. The joint spectrum detection module includes an optical fiber collimator, an optical fiber, an optical switch and a spectrum analyzer, which is used to perform spectrum detection on the two output optical signals at the same time;

Specifically, the two output lights of the beam splitter pass through the fiber collimator and the fiber respectively, enter the optical switch, and then enter the spectrum analyzer.

6. The data processing module includes a platform software system based on Labview or FPGA and Matlab, realizes the collection and storage of spectral signals, analyzes and processes the collected spectral signals, and obtains an estimated value of time delay.

Specifically, the Labview platform that communicates with the optical switch and the spectrum analyzer through the IP protocol sends control commands to control the switching of the optical switch, the setting of the spectrum analyzer, the collection of spectral data and the output data of the built-in analysis function of the spectrum analyzer, and the collection of The received information is stored as a file. Programs written in Matlab or other languages process the data in the file to obtain an estimate of the delay.

The analysis results of the spectrum analyzer are shown in Figures 2 to 7.

Those skilled in the art know that, in addition to implementing the system provided by the present invention and its respective devices in the form of pure computer-readable program codes, the system provided by the present invention and its respective devices can be made by logic gates, Switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers are used to achieve the same function. Therefore, the system provided by the present invention and its various devices can be regarded as a hardware component, and the devices included in it for realizing various functions can be regarded as the structure in the hardware component, and can also be regarded as the implementation method. software module.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essential content of the present invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily, provided that there is no conflict.

Claims (8)

1. A high-sensitivity optical time delay estimation system, comprising: the system comprises a light source module, a polarization state pre-modulation module, an optical time delay sensing module, a combined spectrum detection module, a data processing module and a polarization state post-selection module;

the light source module is used for generating an original light signal, and the central wavelength of the original light signal is recorded as lambda₀；

The polarization state pre-modulation module is used for pre-modulating the polarization of an original optical signal to generate first output light;

the optical time delay sensing module is used for loading an optical time delay value to be measured to the first output light to generate second output light;

the polarization state post-selection module is used for performing projection decomposition on the second output light according to a specified polarization state to generate two paths of output light, namely third output light and fourth output light;

the combined spectrum detection module is used for simultaneously performing spectrum detection on the third output light and the fourth output light and outputting a spectrum signal;

the data processing module collects and stores the output spectrum signals, analyzes and processes the collected spectrum signals and obtains an estimated value of optical time delay;

the combined spectrum detection module comprises: a first optical fiber collimator (6), a second optical fiber collimator (7) and a spectrometer (8) with an optical switch module;

the combined spectrum detection module: the two paths of output light generated by the selection module after polarization state enter optical fibers connected with a spectrometer through optical fiber coupling equipment respectively and are further collected by the spectrometer to obtain spectral information;

the spectral distribution of the transmitted light collected by the spectrometer is:

P₁(λ_i) A wavelength distribution representing a spectrum of the transmitted light signal;

P₀(λ_i) A wavelength distribution representing the spectrum of the original optical signal;

λ₀expressing the initial average wavelength value, represented by formula ∑_iP(λ_i)λ_iComputing

λ_iA scale value of a certain wavelength which can be detected by a spectrometer;

c represents the speed of light in vacuum;

represents a real number much less than 1;

τ represents the optical time delay;

A_w1(λ_i) Represents a complex value, calculated by:

Im[A_w1(λ_i)]is represented by A_w1(λ_i) An imaginary part of (d);

the spectral distribution of the reflected light collected by the spectrometer is as follows:

P₂(λ_i) Representing the wavelength of the spectrum of the reflected light signalDistributing;

A_w2(λ_i) Represents a complex value, calculated by:

Im[A_w2(λ_i)]is represented by A_w2(λ_i) The imaginary part of (c).

2. The high-sensitivity optical time delay estimation system of claim 1, wherein the polarization state pre-modulation module comprises: a linear polarizer (1) and a first quarter-wave plate (2),

the polarization state pre-modulation module:

the method comprises the steps that an original light signal generated by a light source module passes through a linear polarizer (1) and a first quarter-wave plate (2) to generate first output light, the direction of the linear polarizer is set to form a first preset included angle with a horizontal plane, and the direction of the first quarter-wave plate is set to form a first preset included angle with the direction of the linear polarizer

An angle, the polarization state of the first output light being recorded as a pre-selected polarization state, the notation being:

wherein,

representing a pre-selected polarization state;

i H > and I V > respectively represent a horizontal polarization state and a vertical polarization state;

represents a real number much less than 1;

e^-iCrepresents the modulation phase value-C;

e^iCrepresents the modulation phase value C;

the phase value C to be modulated is calculated by:

wherein,

ω represents the angular frequency of the optical signal,

ω₀an average value representing the angular frequency of the optical signal;

the optical time delay perception module comprises: a Sory-Babinet compensator (3);

the optical time delay perception module: making the first output light pass through a Sorri-Babinet compensator to generate a second output light;

the direction of the Sorrill-Babinet compensator is set to form a second preset included angle with the linear polaroid, compared with the first output light, a section of propagation optical time delay is added between the horizontal polarization component and the vertical polarization component of the second output light, and the optical time delay is recorded as tau.

3. The high-sensitivity optical time delay estimation system of claim 1, wherein the polarization post-selection module comprises: a second quarter wave plate (4) and a polarizing beam splitter (5);

the polarization state post-selection module: the second output light passes through a second quarter-wave plate (4) and a polarization beam splitter (5) to generate two paths of output light, namely third output light and fourth output light;

the second quarter-wave plate (4) is arranged to form a third preset included angle with the linear polaroid, and the polarization direction of the polarization beam splitter is arranged to form a fourth preset included angle with the linear polaroid.

4. The high-sensitivity optical time delay estimation system of claim 1, wherein the data processing module collects and stores spectral information obtained by the combined spectrum detection module;

according to the spectrum information obtained by the combined spectrum detection module, the following average wavelength value is defined and calculated:

represents the average wavelength value calculated from the measured data;

the estimated value of the time delay is solved by the following formula:

wherein,

tau represents the optical time delay to be measured, namely the estimated value of the time delay;

c represents the speed of light in vacuum;

λ represents the wavelength shift amount by averaging the wavelength values

Subtracting the initial average wavelength value lambda of the input light₀Thus obtaining the product.

5. A method for high-sensitivity optical time delay estimation, comprising: the method comprises the steps of light source generation, polarization state pre-modulation, optical time delay perception, joint spectrum detection, data processing and polarization state post-selection;

the light source generating step is used for generating an original light signal, and the central wavelength of the original light signal is recorded as lambda₀；

The polarization state pre-modulation step is used for pre-modulating the polarization of the original optical signal to generate first output light;

the optical time delay sensing step is used for loading an optical time delay value to be measured to the first output light to generate second output light;

the polarization state post-selection step is used for performing projection decomposition on the second output light according to a specified polarization state to generate two paths of output light, namely third output light and fourth output light;

the combined spectrum detection step is used for simultaneously carrying out spectrum detection on the third output light and the fourth output light and outputting a spectrum signal;

the data processing step collects and stores the output spectrum signals, and analyzes and processes the collected spectrum signals to obtain an estimated value of optical time delay;

the polarization state post-selection step: the second output light passes through a second quarter-wave plate (4) and a polarization beam splitter (5) to generate two paths of output light, namely third output light and fourth output light;

the second quarter-wave plate is arranged to form a third preset included angle with the linear polarizer, and the polarization direction of the polarization beam splitter is arranged to form a fourth preset included angle with the linear polarizer;

the combined spectrum detection step comprises: the two paths of output light generated in the step of selecting after polarization state enter optical fibers connected with a spectrometer through optical fiber coupling equipment respectively and are further collected by the spectrometer to obtain spectral information;

the spectral distribution of the transmitted light collected by the spectrometer is:

P₁(λ_i) A wavelength distribution representing a spectrum of the transmitted light signal;

P₀(λ_i) A wavelength distribution representing the spectrum of the original optical signal;

λ₀expressing the initial average wavelength value, represented by formula ∑_iP(λ_i)λ_iComputing

λ_iA scale value of a certain wavelength which can be detected by a spectrometer;

c represents the speed of light in vacuum;

represents a real number much less than 1;

τ represents the optical time delay;

A_w1(λ_i) Represents a complex value, calculated by:

Im[A_w1(λ_i)]is represented by A_w1(λ_i) An imaginary part of (d);

the spectral distribution of the reflected light collected by the spectrometer is as follows:

P₂(λ_i) A wavelength distribution representing a spectrum of the reflected light signal;

A_w2(λ_i) Represents a complex value, calculated by:

Im[A_w2(λ_i)]is represented by A_w2(λ_i) The imaginary part of (c).

6. The method according to claim 5, wherein the polarization pre-modulation step:

the original light signal generated in the light source generating step passes through a linear polaroid (1) and a first quarter-wave plate (2) to generate first output light, the direction of the linear polaroid is set to form a first preset included angle with the horizontal plane, and the direction of the first quarter-wave plate is set to form a first preset included angle with the direction of the linear polaroid

An angle, the polarization state of the first output light being recorded as a pre-selected polarization state, the notation being:

wherein,

representing a pre-selected polarization state;

i H > and I V > respectively represent a horizontal polarization state and a vertical polarization state;

represents a real number much less than 1;

e^-iCrepresents the modulation phase value-C;

e^iCrepresents the modulation phase value C;

the phase value C to be modulated is calculated by:

wherein,

ω represents the angular frequency of the optical signal,

ω₀an average value representing the angular frequency of the optical signal;

the optical time delay sensing step: passing the first output light through a Sorri-Babinet compensator (3) to produce a second output light;

the direction of the Sorrill-Babinet compensator is set to form a second preset included angle with the linear polaroid, compared with the first output light, a section of propagation optical time delay is added between the horizontal polarization component and the vertical polarization component of the second output light, and the optical time delay is recorded as tau.

7. The high-sensitivity optical time delay estimation method according to claim 6, wherein the data processing step collects and stores the spectral information obtained by the combined spectrum detection step;

defining and calculating the following average wavelength values according to the spectrum information obtained in the combined spectrum detection step:

represents the average wavelength value calculated from the measured data;

the estimated value of the time delay is solved by the following formula:

wherein,

tau represents the optical time delay to be measured, namely the estimated value of the time delay;

c represents the speed of light in vacuum;

λ represents the wavelength shift amount by averaging the wavelength values

Subtracting the initial average wavelength value lambda of the input light₀Thus obtaining the product.

8. A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the high-sensitivity optical time delay estimation method of any one of claims 5 to 7.

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